Presently, a backlight module of a liquid crystal display device generally employs LEDs (light-emitting diode) as its light sources. Backlight modules can be classified into a direct-downward type and a side-entrance type depending on distribution positions of the light sources. An LED light strip in a backlight module of a side-entrance type is located at a side edge of a light guiding plate, and such a backlight module is mainly applied in notebooks, palm computers, cell phones and similar small-sized display devices. With the continuously improvement of the LED-related technologies, backlight modules of the side-entrance type also begin to be applied in larger-sized display devices to provide even better visual experience for the users.
With the continuously improvement of the technologies, characteristics such as being ultrathin, high-lightening, and narrow frame have become the main stream in the consumer market for the display products; in order to meet the development trend of the narrow frame, a width of a light-shielding tape is also getting narrower. However, due to the narrow width of the light-shielding tape, a side region of a backlight module frame has relatively concentrated light (as shown by a circled region in FIG. 1), where bright lines are easily to be generated, which may cause poor image quality and have bad influence on display quality of the display device.